Deaerating apparatus



March 5, 1968 w oss ET AL 3,371,865

DEAERATING APPARATUS Filed May 20, 1966 2 Sheets-Sheet 1 SOLVE/417V OF6035s In L/QU/O INVENTORS I l 7/; u/vone 50/4/16 Pam/r ra c 0 70 swm:r/mz GENE M Pass 7 I Dav/a 5". F033 ATTORNEYS March 5, 1968 G R055 ET AL3,371,865

DEAERATING APPARATUS Filed May 20, 1966 2 Shets-Sheet 2 I N V EN TORS627v: h. Foss Dr? V/@ :5: Pass i wLKm q zfwzw United States PatentOfiice 3,371,865 Patented Mar. 5, 1968 3,371,865 DEAERATHNG APPARATUSGene W. Ross and David S. Ross, Lorain, Ohio, assignors,

by mesne assignments, to Ritter Pfaudlcr Corp, Rochester, N.Y., acorporation of New York Filed May 20, 1966, Ser. No. 551,677 8 (Ilaims.(Cl. 237-68) This invention relates to the removal of dissolved gasesfrom a liquid by subjecting the liquid to a vacuum and in particular toimproved equipment for carrying out the vacuum treatment. It alsorelates to improvements in the deaeration of water in heating systems,particularly steam heating systems.

Degasification, or more specifically, deaeration of liquids hasapplication in the fields of heating, water treatment, distillation,concentration, drying and hardness removal and other installations wherescale and corrosion are a source of high operating and equipment costs.One example of such an installation is a steam heating system of thekind in which a central boiler system supplies steam to one or morelocations, for example separate buildings, which are remote from theboiler system. In installations of this kind it is conventional toreturn the condensate from each location to the boiler system. Thecondensate, as it forms, invariably becomes contaminated with dissolvedgases with the result that the pipe or pipes which return the condensateto the boiler system are subjected to corrosion. In many installationsthe main condensate return line has a useful life of only a few years.

Vacuum degasifiers of one known type operate by pumping a portion of abatch of liquid out of a sealed tank, the displaced portion of theliquid producing a boiling-point vacuum in the tank. The vacuum causes asmall part of the liquid to boil and at the same time causes thedissolved gases to come out of solution and rise to the surface of theremaining liquid in the form of small bubbles. When the vacuum isrelieved and fresh liquid is re supplied to the tank, the gases whichwere previously libcrated are forced by displacement out of a vent atthe top of the tank, and the pumping process is repeated after againsealing the tank. The operation of this type of system is based on theknown principle that the solubility of most gases in a liquid approacheszero at the boiling point of the liquid.

From the above description it will be apparent that the portion ofliquid which is first pumped out of a newly sealed tank has not beensubjected to a vacuum for any appreciable period and therefore has notbeen degasified. In one known form of this type of equipment thefirstpumped portion of liquid, which may still contain dissolved gas, isintroduced into the system which receives the liquid from the pump, suchas the boiler of a steam heating system. Obviously, this is anundesirable feature because over a long period of time a considerablevol- 'ume of gas will be introduced into the boiler. In a more complexform of known equipment the deaeration equipment includes two deaerationtanks and a special piping and valve arrangement which, together with apump, withholds the first-pumped liquid and sends only completelydeaerated liquid to the system. This type of equipment is extremelyeificient but represents a capital investment which may not be warrantedin a small heating plant.

A full disclosure of the first-mentioned arrangement may be found inBaker Patent 2,339,369, issued Jan. 18,

1944, and a full disclosure of the more complex arrangement may be foundin Baker Patents 2,357,445, issued Sept. 5, 1944, 2,735,623, issued Feb.21, 1956, 2,997,129, issued Aug. 22, 1961 and 3,104,163, issued Sept.17, 1963.

It is one of the objects of the present invention to reduce thecorrosion in the condensate return line of steam generating systems,particularly where the boiler is remote from the location at which thesteam condenses, by providing a low-cost deaerating system at thecondensing location for directly receiving condensate and for deliveringdeaerated condensate to the condensate return line. In a preferredarrangement the deaerating system is arranged below the level of thesteam condensing equipment to receive condensate by gravity and toemploy the gravity fiow to contribute to the operation of the system.

It is another object of the present invention to provide a low-cost,simply constructed form of displacement type vacuum degasificationequipment which withholds the first-pumped portion of liquid without theuse of a double deaeration tank and an interconnecting pipe and valvearrangement.

It is a still more specific object to provide a low-cost form ofdegasification equipment having a single deaeration tank from whichliquid is pumped to create a deaerating vacuum therein and a relativelysmall inexpensive surge tank associated with the outlet of the pump in amanner to accept and hold the first-pumped portion of liquid andsubsequently to return that portion to the deaerating tank.

The invention will be further understood from the following detaileddescription taken with the drawings in which:

FIGURE 1 is a schematic elevational view, partly broken away, of a steamheating installation including a condensate deaerating and return systemembodying the principles of the present invention;

FIGURE 2 is a graph illustrating the operation of the deaerating unit ofFIGURE 1;

FIGURE 3 is a schematic elevational view of a second embodiment of acondensate deaerating system; and

FIGURE 4 is a schematic elevational view, partly broken away, of a thirdembodiment of the deaerating unit of FIGURE 1. 1

Referring to FIGURE 1 there is shown a steam generating installationwhich includes a main boiler system 2, a main steam line 3, a maincondensate return line 4 and three steam consumption stationsremote'from the boiler system 2. The latter is illustrated as includinga boiler 5, a steam condensate storage tank 6 and a piping arrangement 7for delivering condensate to the boiler 5 as required. It will .beunderstood that the system 2 may include any equipment conventionallyemployed in boiler feed arrangements and need not necessarily includethe storage tank 6. For simplicity each of the steam consumptionstations may be considered as a separate building which is to be heated,the heating equipment including radiators 8, 8a and 8b or the like and asteam trap 9, 9a and 912 for passing condensed steam out of the heatingequipment. According to the principles of one feature of the presentinvention the main condensate return line 4, which may be of greatlength, is protected from internal corrosion by providing a low-costvacuum-type condensate deaerating system at each steam consumptionstation.

,These low-cost deaerating systems, of which a preferred construction isillustrated in detail at and schematically at 10a and 10b, remove thedissolved gas from the condensate soon after it forms with the resultthat the main condensate line 4 is not subjected to the corrosive effectof normal, gas-containing condensate. Each system 10, 10a and 10b isarranged to receive condensate from the respective steam trap 9 bygravity, and the gravity flow is employed to contribute to the operationof the system as will become apparent from the following description.

Referring to the lower portion of FIGURE 1 it will be seen that thecondensate deaerating system 10 is disposed below the level of therespective radiators 8 and steam trap 9 and below the level of the maincondensate return line 4. Fresh condensate enters the system 10 bygravity from the trap 9 through a line 11, and deaerated condensate ispumped to the main condensate line 4 through a line 12. Deaeration offresh condensate takes place in a deaerating tank 13 when the latter hasbeen sealed and some of the liquid 14 therein is displaced by means of acentrifugal pump 15. The pump 15 is disposed below the liquid level inthe tank 13 and has its inlet connected to the lower portion of the tank13 by a pipe 16, the latter forming both inlet and outlet for the tank13.

The pump 15 forms part of a conventional motorpump unit which includesan electric motor 17 and shaft 18 for driving a rotor 19 within a pumpcasing 20. In the illustrated embodiment the pump 15 is provided with ashaft lubricating and sealing arrangement which also contributes to thedeaerating function of the apparatus. The arrangement includes a housing21 surrounding the shaft 18 and a bleed conduit 22 extending between thetank 13 and the space between the housing 21 and the shaft 18. The bleedconduit 22 contains a valve 23 which may be adjusted to control the flowof water from the housing 21 into the tank 13.

The outlet of the pump 15 is connected to a discharge pipe 28 whichleads to a hold-up and discharge portion of the system. The end of thepipe 28, remote from the pump casing 20, connects with the line 11through a branch 30 and a valve 36 which permits liquid flow only fromthe line 11 into the pipe 28. Conveniently, the valve 36 is a checkvalve which opens automatically when the pressure in the line 11 exceedsthe pressure in the condensate receiving pipe 28. To protect the valve36 and the pump 15 from solid matter entering with condensate from theline 11, the branch includes a conventional screen and flush unit 33.Intermediate its ends the pipe 28 communicates with an upwardlyextending branch 34 which leads to a surge or holdup tank and to anotherbranch 32. The latter connects with the line 12 through a valve 38which, conveniently, is a check valve arranged to pass liquid into theline 12 when the pressure in the branch is high enough to open the valveagainst the pressure in the line 12. If necessary, the valve 38 may bebiased toward a closed position. Both valves 38 and 36 may be providedwith separate controls for opening and closing them in the desiredsequence although the use of check valves is preferred from thestandpoint of cost and simplicity.

The liquid holdup tank 40 which is of much smaller volume than thedeaerating tank 13, is disposed above the pump discharge pipe 28 andconnects at its lower end with the branch 34. A body of condensateliquid 42 and an overlying capacitive gas cushion 44 are containedWithin the tank 40. The volume of the cushion 44 may be adjusted byintroducing or removing gas through a valved tap 46 located on top ofthe tank 40.

Referring again to the deaerating tank 13 it will be seen that the topof the tank is provided with a gas vent line 48 containing a check valve50 for passing gas only out of the tank 13. The top of the tank 13 isalso provided with an electrically operated liquid level sensing device52 for controlling the operation of the deaerating pump motor 17 throughan electrical control line 54. The sensing device includes an upperprobe 56 which effects a pump-on signal when condensate 14 rises tolevel A at the lower end of the probe 56. A lower probe 58 effects apump-off signal when condensate falls to level C at the lower end of theprobe 58.

Referring to FIGURE 3 there is shown a deaerating system 10 whichdiffers from the system 10 of FIGURE 1 in the piping by which condensateenters and leaves the system. In the FIGURE 3 construction a deaeratingtank 13 is provided with separate pipes 60 and 62 for transferringcondensate into and out of the tank 13', respectively. The inlet pipe 60receives fresh condensate from a steam heating system, such as thatillustrated in FIGURE 1, through a line 11 and passes the condensatethrough a pressure-to-close valve 64 into the deaerating tank 13'. Theoutlet pipe 62 conducts condensate from the tank 13 to the inlet of apump 15. The pump discharge line 2 8' divides into two branches 32 and34, the former connecting with the bottom of a holdup tank 40' and thelatter connecting with the condensate return line 12' through a checkvalve 38. The holdup tank 40', like the holdup tank 40 of FIGURE 1,contains a gas cushion 44 overlying a body of condensate 42'.

The pump 15' is controlled by a liquid level sensitive control system52, 54' associated with the deaerating tank 13 which turns the pump onwhen the liquid rises to the level A and turns the pump off when theliquid drops to the level C. The condensate inlet valve 64 is normallyopen and is closed by operation of the pump 15 by means of a pressuresignal transmitted from the pump discharge line 28, to the valve 64through a control line 66.

FIGURE 4 illustrates a modified deaerator unit 10 in which provision ismade for recirculating a portion of the withdrawn liquid back to thedeaerator tank 13 after the liquid 14" in the tank 13" has beenpartially pumped out. The apparatus is similar to that of FIGURE 1 inthat liquid enters and leaves the tank 13 through a single pipe 28 and apump 15". However, in the FIG- URE 4 arrangement there is, in addition,a bleed line 70 connecting the pipe 28 with the upper portion of thetank 13", The bleed line 70 contains a valve 72 which is controlled by afloat 74 within the tank 13". The float 74 and an associated controlarrangement 76 maintain the valve 72 closed when the liquid 14" withinthe tank 13" is high. When the liquid level drops to the dottedlineposition of the float 74 as a result of the operation of the pump 15",the valve 72 opens to allow a relatively small proportion of the flow inpipe 28" to return to the tank 13" through the bleed line 70. Theconnection of the line 70 is shown as being well above the level of theliquid 14" at which the valve 72 opens so that the recirculated liquidis sprayed into the tank 13".

During operation of the heating installation of FIG- URE 1 freshcondensate drains by gravity into the deaerating tank 13 through thecondensate line 11, the check valve 36 and the pump 15. When the levelof condensate 14 in the deaerating tank 13 rises to the bottom of theprobe 56 a pump-on signal is transmitted to the pump motor 17 throughthe electrical control line 54. During accumulation of condensate 14 inthe tank 13 gases above the liquid level are forced by displacementthrough the check valve 50 in the vent line 48 and discharged to theatmosphere. However, as soon as the pump 15 begins to operate, the checkvalve 50 closes thus sealing the tank against entry of either gas orliquid.

Upon operation of the pump 15 a boiling point vacuum is created in thetank 13 as a result of the sealing action of the check valve 50 and thedisplacement of some of the condensate from the tank 13. The vacuum verysoon reduces to zero the solubility of dissolved gas in the remainingcondensate 14 with the result that the gas comes out of solution andrises to the surface in the form of small bubbles 68. Simultaneously thegas-containing condensate which is first pumped out of the tank 13passes into the pump discharge line 28 and upwardly into the holdup tank46 through the branch line 34. At this time no condensate flows into thereturn line 12 through may be spring loaded toward a closed position.Alternatively, the valve 38 may be caused to open under the control of apressure signal from the pump or after a predetermined period of pumpoperation. No flow occurs in the branch line 36, because the outletpressure of the pump in the latter is higher than in the line ll therebycausing the check valve 36 to remain closed.

As the fresh gas-containing condensate is pumped into the holdup tank idthe gas cushion 44 is gradually compressed, and the pressure in the pumpdischarge line 28 gradually rises. When the pressure becomes suflicientto overcome the pressure difference across the check valve 38, thelatter opens and permits deaerated condensate to be forced from the pumpdischarge line 28 through the branch line 32 and into the line 12. Themain condensate line 3 will therefore receive only deaerated water.Since this line may be of great length, its protection from corrosionwill result in a savings which in almost all cases will be more thanoffset by the cost of the deaeration system Ill. The portion ofcondensate which was previously pumped into the holdup tank 4d remainsin the tank til, because the pressure of the water flowing in the pumpdischarge line 28 is slightly higher than the static pressure in thetank dil.

During operation of the pump I5 the vacuum in the tank I3'will drawwater through the bleed conduit 22 from the housing 21 therebylubricating the shaft I3. In addition, the stream of water entering thetank I3 agitates the liquid lid thereby increasing the rate at whichdissolved gas comes out of solution. A further effect of the enteringstream results from the fact that the water passing into the tank 133from the bleed conduit 22 is subjected to a deaerating vacuum for alonger period of time than the water which does not become by-passedthrough the bleed conduit 22.

When the condensate Id has been pumped down to the bottom of the probe53, illustrated by the dashed line C, a pump-off signal is transmittedthrough the control line 54 to shut off the motor 17. The pressure inthe pump discharge line begins to drop, and thereupon the gas cushion 44in the top of the holdup tank 4ft expands and forces some of thecondensate 42 from the tank iii into the line 23 and then in a reversedirection through the non-operating pump 15 and into the deaerating tank13. After the pressure in the tank MP has been thus re lieved, the checkvalve 36 opens and gas-containing condensate from the line Ill flows bygravity into the line 28 and subsequently into the tank 13.Simultaneously the check valve 50 opens and permits the liberated gasesin the tank 13 to be displaced to atmosphere through the vent 48, 5%.

It will thus be seen that the first-pumped, air containing portion ofcondensate 14- which is pumped out of the deaerating tank 13 is withheldfrom the return line 112 and is subsequently returned to the tank 13 fordeaeration. The effect of Withholding this first-pumped portion isillustrated graphically in FIGURE 2 where the solubility of gases in agiven liquid at a constant temperature is plotted against time under aboiling point vaccum. It will be seen that the concentration of gases ina liquid drops rapidly in the first few moments of vacuum and then dropsvery much more slowly. Thus, substantially all dissolved gas isliberated between the initiation of a boiling point vacuum, illustratedat A, and a time B occurring shortly thereafter. At a later time,illustrated at C, only a small additional amount of gas has beenliberated from solution. Applying the graph to the FIGURE 1 system itwill be seen that substantially all dissolved gas will be liberated fromthe condensate M in the deaerating tank 13 within a relatively shorttime after starting the pump 15". Accordingly, the volume of the holduptank 40 need not be large, and in the illustrated arrangement it isconstructed to hold only that amount of condensate which is pumpedduring the period of time from A to B on the graph of FIGURE 2. Thedashed lines A, B and C in FIGURE 1 indicate the level of condensate inthe tank 13 at the times A, B and C, respectively. It will thus beappreciated that in the most economical construction the holdup tank it)is constructed no larger than necessary. For different systems the sizeof the tank W will increase with an increase in the capacity of the pump15, but not necessarily with an increase in the size of the deaeratingtank 13.

It will also be apparent from the graph of FIGURE 2 that the bleed waterentering the tank ll3 will contribute to the gas removal efficiency ofthe apparatus, because the bleed Water will be maintained under a vacuumfor a relatively long period of time due to its recirculation betweenpump 15 and tank 13.

The construction and operation of the deaerating systems Ida and lltlbare the same as the system It).

The operation of the FIGURE 3 system is similar to the operation of theFIGURE 1 system. However, in the FIGURE 3 system condensate from theheating system (not shown) enters the deaerating tank 13 through aseparate line 45b rather than through the deaerating pump 15' as in theFIGURE 1 system. When the pump 15' starts after receiving a purnp-onsignal through the control line 54', the deaerating tank 13 becomessealed by the closing of the check valve and by the closing of the valve64. The latter is normally open to permit condensate to drain by gravitythrough line I l into the tank 13, but closes when a pressure signal isdelivered thereto through the control line 6d from the pump dischargeline 28'. The pumping of condensate from the sealed tank 13 immediatelycreates a boiling point vacuum therein and dissolved gas begins to beliberated from the condensate in accordance with the relationshipillustrated in FIGURE 2.

The first-pumped portion of condensate, which is a mixture of completelyundeaerated water and partially deaerated water, passes upwardly intothe holdup tank 40' against the gas cushion 44. When the pressure in thepump discharge line 28 becomes sufficient to overcome the pressuredifierence across the check valve 38, the latter opens and permitssubstantially completely deaerated Water to flow from the line 28 intothe return line 12'. The holdup tank 40' is of a size which will accepta volume of liquid equal to the volume between levels A and B in FIGURE3, this volume representing the volume pumped between time A and time Bin FIGURE 2. At time C and level C the pump 15 stops, check valve 38'closes and some of the water 42' in the surge tank is forced back intothe deaerating tank 13 in a reverse direction through the pump 15. Whenthe pressure in the pump discharge line 28 drops, the valve 64 in thecondensate inlet line opens and permits condensate to flow by gravityinto the tank 13' thereby displacing previously liberated gases throughthe check valve 50 and the vent 48.

The operation of the deaerator 10 of FIGURE 4 is the same as thedeaerator of FIGURE l with the additional effect produced by therecirculation of liquid through bleed line 70. The bleed line isinoperative at the beginning of a pump-out operation, because the float74- and control arrangement 76 maintain the valve 72 closed. After thepump 15" operates for a short time, the float 74 drops to thedotted-line position, and the valve '72 opens. Since the liquid nowflowing through the pipe 23" has been subjected to a vacuum in the tank13 it is at least partially deaerated. The pontion which returns to thetop of the tank 13" is sprayed into the vacuum space above the liquid 14with the result that the spray becomes highly deaerated. It will also beappreciated that recirculation through the bleed line 70 increases theaverage time to which the liquid in the pipe 28 has been subjected to avacuum. From a considera- 7 tion of the graph of FIGURE 2 it will beseen that the liquid in the pipe 28" will therefore contain lessdissolved gas than if no recirculation was present.

In the interest of further economy it may be desirable under somecircumstances to omit the holdup tank feature of the present invention.This, of course, would return the first-pumped, gas-containingcondensate to the main condensate line, but under some circumstances thesmall amount of dissolved gas might be deemed insufficient to warrantthe investment in the holdup tank. It is known, of course, to employdeaerators at the boiler as part of the boiler feed system, and in theevent that a boiler feed deaerator were employed the small amount of gasin the main condensate would be removed prior to feeding the condensateto the boiler. It is important, however, that the deaerating systems,regardless of whether a holdup tank is employed, be associated with theremote stations and be arranged so that filling of the deaerating tanksand consequent venting of gases therefrom is accomplished automaticallyby the pressure at which the condensate is available. In the case ofsteam systems a gravity condensate feed can be obtained because it isusually convenient to locate the deaerating system below the level ofthe steam condensing equipment. However, the invention is applicable toany liquid processing installation in which gas-containing liquid isavailable at a pressure, either static head or produced by a pump, whichis sufficient to force the liquid into the deaerating tank.

It will be understood, also, that the utility of the hereindescribedcombination of a holdup tank with a deaerating tank is not limited toits incorporation in a particular type of liquid processinginstallation. That is, the combination of a holdup tank with adeaerating tank may be employed wherever it is desired to degasify aliquid regardless of the source of the gas-containing liquid or thedestination of the degasified liquid.

From the above descriptions it will be apparent that the invention isnot limited to the precise embodiments illustrated and that thedisclosed details are exemplary of the principles involved and are notintended to be limiting except as they appear in the appended claims.

What is claimed is:

1. Liquid degasifying apparatus comprising:

a degasification tank for containing a batch of liquid which is to bedegasified;

vent valve means in communication with the top of said tank for sealingsaid tank against ingress of fluid when closed and for passing gases outof said tank when open;

a liquid receiving conduit for receiving liquid from said tank; and

means for producing a vacuum in said tank thereby to degasify liquid insaid tank and for conducting substantially completely degasified liquidfrom said tank to said liquid receiving conduit, said means including apump for withdrawing liquid from said tank whereby when said vent valvemeans is closed a degasifying vacuum may be produced in said tank, saidpump having an inlet disposed below the liquid level in said tank and anoutlet, said outlet being connected to said liquid receiving conduit, aholdup tank of lesser volume than said degasification tank and having anupper and a lower portion, said lower portion containing a liquid andbeing in communication with said liquid receiving conduit, said upperportion containing a gas cushion compressible by liquid in said lowerportion and sealed from the atmosphere; and a liquid control valve insaid liquid receiving conduit and located more remotely from said pumpthan the point of communication between said conduit and said holduptank;

whereby When said vent valve and control valve are closed and said pumpis operated, the first-pumped portion of liquid which is withdrawnliquid from said degasification tank is forced into said lower portionof said holdup tank against said gas cushion and whereby When saidliquid control valve is subsequently opened, substantially completelydegasified liquid is passed from said degasification tank through saidliquid control valve.

2. Apparatus as in claim 1 wherein said vent valve is a check valvearranged to pass gases out of said degasification tank when liquid isintroduced thereinto and to close automatically upon creation of avacuum therein and wherein said liquid control valve is a check valvearranged to open under the influence of a predetermined high pressure insaid conduit on the pump side of said check valve whereby substantiallycompletely degasified liquid will be passed automatically by said valveafter said gas cushion has been compressed to said predeterminedpressure.

3. Apparatus as in claim 1 including a liquid inlet conduit connectingat one end with said degasification tank, a normally open valve in saidinlet conduit, and means responsive to operation of said pump forclosing said valve.

4. Apparatus as in claim 1 including a liquid inlet conduit connectingat one end with said liquid receiving conduit, and a check valve in saidinlet conduit arranged to pass liquid into said receiving conduit whenopen.

5. Apparatus as in claim 1 including recirculation conduit means forreturning a portion of the liquid passing through said pump outlet tosaid degasification tank to thereby again subject the portion to adeaerating vacuum, said means including a conduit communicating at oneend with said degasification tank and at its other end with said purnpoutlet.

6. In a steam generating and condensing installation including a boilersystem, steam condensing means remote from said boiler system and asteam condensate return line for conducting condensate from saidcondensing means to said condensate return line, the improvementcomprising;

a low-cost, simply constructed vacuum deaerator located substantially atsaid station for deaerating steam condensate and thereby protecting saidreturn line from steam condensate internal corrosion, said deaeratorincluding a deaerating tank disposed below said steam condensing meansso as to permit gravity flow of condensate into said tank; vent meansassociated with the top of said deaerating tank to pass gases out ofsaid tank upon introduction of condensate into said tank; a vacuumproducing pump disposed below the level of condensate in said tank andconnected to pump condensate out of said tank;

said installation further comprising deaerated condensate conduit meansconnected between said pump and said condensate return line at alocation remote from said boiler system for conducting deaeratedcondensate to said condensate return line; valve means in said conduitmeans for controlling the flow of deaerated condensate into saidcondensate return line; means for opening said valve means when saidpump operates and for closing said valve means when said pump isstopped; a conduit connected at one end to said condensing means and atits other end to said deaerator for conducting fresh condensate to thelatter; valve means in said fresh condensate conduit; and means foropening said last-named valve means when said pump is stopped to therebyallow fresh condensate to flow into said deaerator by gravity, saidmeans being further operative to close said last-named valve means whensaid pump operates.

7. An installation as in claim 6 wherein said other end of said conduitfor conducting fresh condensate from said condensing means to saiddeaerator connects with said deaerated condensate conduit means at alocation between said pump and the valve means in said deaeratedcondensate conduit means whereby fresh con- References Cited densateenters said deaer ating tank by flowing in a re- UNITED STATES PATENTSverse d1rect10n through sald pump.

8. An installation as in claim 6 wherein said other end 1,644,11410/1927 Dunham X of said conduit for conducting fresh condensate fromsaid 5 2,626,756 1/ 1953 Afbogfist 237-9 condensing means to saiddeaerator connects with said deaerating tank. EDWARD J. MICHAEL, PrimaryExaminer.

1. LIQUID DEGASIFYING APPARATUS COMPRISING: A DEGASIFICATION TANK FORCONTAINING A BATCH OF LIQUID WHICH IS TO BE DESASIFIED; VENT VALVE MEANSIN COMMUNICATION WITH THE TOP OF SAID TANK FOR SEALING SAID TANK AGAINSTINGRESS OF FLUID WHEN CLSED AND FOR PASSING GASES OUT OF SAID TANK WHENOPEN; A LIQUID RECEIVING CONDUIT FOR RECEIVING LIQUID FROM SAID TANK;AND MEANS FOR PRODUCING A VACUUM IN SAID TANK THEREBY TO DEGASIFY LIQUIDIN SAID TANK AND FOR CONDUCTING SUBSTANTIALLY COMPLETELY DEGASIFIEDLIQUID FROM SAID TANK TO SAID LIQUID RECEIVING CONDUIT, SAID MEANSINCLUDING A PUMP FOR WITHDRAWING LIQUID FROM SAID TANK WHEREBY WHEN SAIDVENT VALVE MEANS IS CLOSED A DEGASIFYING VACUUM MAY BE PRODUCED IN SAIDTANK, SAID PUMP HAVING AN INLET DISPOSED BELOW THE LIQUID LEVEL IN SAIDTANK AND AN OUTLET, SAID OUTLET BEING CONNECTED TO SAID LIQUID RECEIVINGCONDUIT, A HOLDUP TANK OF LESSER VOLUME THAN SAID DEGASFICATION TANK ANDHAVING AN UPPER AND A LOWER PORTION, SAID LOWER PORTION CONTAINING ALIQUID AND BEING IN COMMUNICATION WITH SAID LIQUID RECEIVING CONDUIT,SAID UPPER PORTION CONTAINING A GAS CUSHION COMPRESSIBLE BY LIQUID INSAID LOWER PORTION AND SEALED FROM THE ATMOSPHERE; AND A LIQUID CONTROLVALVE IN SAID LIQUID RECEIVING CONDUIT AND LOCATED MORE REMOTELY FROMSAID PUMP THEN THE POINT OF COMMUNICATION BETWEEN SAID CONDUIT AND SAIDHOLDUP TANK; WHEREBY WHEN SAID VENT VALVE AND CONTROL VALVE ARE CLOSEDAND SAID PUMP IS OPERATED, THE FIRST-PUMPED PORTION OF LIQUID WHICH ISWITHDRAWN LIQUID FROM SAID DEGASIFICATION TANK IS FORCED INTO SAID LOWERPORTION OF SAID HOLDUP TANK AGAINST SAID GAS CUSHION AND WHEREBY WHENSAID LIQUID CONTROL VALVE IS SUBSEQUENTLY OPENED, SUBSTANTIALLYCOMPLETELY DEGASIFIED LIQUID IS PASSED FROM SAID DEGASIFICATION TANKTHROUGH SAID LIQUID CONTROL VALVE.